Abstract: A method, vector, and kit are provided for selectively isolating genes encoding membrane-bound proteins by fusing proteins to a secretable protein having a binding affinity to an antigen (e.g., an antibody), expressing these fusions in host cells, and selectively isolating individual host cells by their ability to bind the antigen via the fusion protein. Host cells expressing fusion proteins that do not contain a membrane binding domain will be relatively unable to bind the antigen, since the fusion proteins in those cells are secreted and unattached to their host cells. The method, vector, and kit disclosed herein are particularly useful for identifying genes for membrane-bound proteins represented in cDNA libraries.

Abstract: Anti-human Mpl antibodies were prepared, and from these three types of antibodies with strong binding activity were selected. An expression system for single-chain antibodies derived from these selected antibodies was constructed using genetic engineering techniques. The anti-human Mpl antibodies and anti-human Mpl single-chain antibodies were assessed for TPO-like agonist activity using BaF3-human Mpl that proliferates TPO-dependently. It was found that while the anti-human Mpl antibodies did not exhibit agonistic activity, the anti-human Mpl single-chain antibodies showed agonistic activity. This shows that when screening for modified antibodies with agonistic activity, it is beneficial to determine agonistic activity after modifying antibodies with antigen-binding activity.

Abstract: A DNA encoding a novel protein SMAP-1 having a signal sequence was successfully isolated by screening a cDNA library derived from human fetal hepatocyte using the TMT method developed originally by the inventors. Based on the expression pattern and structural properties, SMAP-1 was suggested to be a molecule playing an important role in living cells.

Abstract: A method for isolating a gene encoding a membrane-bound protein characterized by fusing a functional protein with a fused protein itself, which differs from the existing TMT method in which an epitope recognized by an antibody is carried in a fused protein. This method enabled selective isolation of a gene encoding a membrane-bound protein.

Abstract: A method for isolating a gene encoding a membrane-bound protein characterized by fusing a functional protein with a fused protein itself, which differs from the existing TMT method in which an epitope recognized by an antibody is carried in a fused protein. This method enabled selective isolation of a gene encoding a membrane-bound protein.

Abstract: A method and kit are provided for selectively isolating genes encoding membrane-bound proteins by fusing proteins to a secretable protein having a binding affinity to an antigen (e.g., an antibody), expressing these fusions in host cells, and selectively isolating individual host cells by their ability to bind the antigen via the fusion protein. Host cells expressing fusion proteins that do not contain a membrane binding domain will be relatively unable to bind the antigen, since the fusion proteins in those cells are secreted and unattached to their host cells. The method and kit disclosed herein are particularly useful for identifying genes for membrane-bound proteins represented in cDNA libraries.

Abstract: A DNA encoding a novel protein SMAP-1 having a signal sequence was successfully isolated by screening a cDNA library derived from human fetal hepatocyte using the TMT method developed originally by the inventors. Based on the expression pattern and structural properties, SMAP-1 was suggested to be a molecule playing an important role in living cells.